Birth defects are more likely to occur in Appalachian counties with mountaintop removal coal mining — including Eastern Kentucky — than in other counties in the region, according to a new study.

The study, published last month in the peer-reviewed journal Environmental Research, suggests that birth defects could result from air and water pollution created by mountaintop removal, including mercury, lead and arsenic, which have been shown to pose risks to fetal development.

The study stops short of blaming mountaintop removal for birth defects. But its authors said they tried to account for other possible causes, such as higher rates of smoking, less education and poorer prenatal care among expectant mothers in mining counties. The common factor seemed to be proximity to the blasting of mountains to remove coal, they said.

"Technically it's true that we don't have direct environmental data that we can link in this study," said co-author Michael Hendryx, associate professor of community medicine at West Virginia University.

"But if you look over the whole set of research documenting air and water quality problems caused by mountaintop removal, I think we've passed the point where we can say we don't really know enough and we have to study more," Hendryx said.